The highly tortuous and permeable vascular network in tumors creates regions of elevated hypertension and fluid shear stresses within the tumor microenvironment. While research has shown that fluid dynamics of the tumor vasculature can reduce uptake of therapeutic agents, the underlying role of these hemodynamic stresses in regulating endothelial-tumor cell signaling, tumor growth, and neovascularization is not well known. The potential of anti-angiogenic therapies to treat highly vascularized tumors is profound; however, the efficacy of these treatments remains insufficient. The primary challenge in translating anti-angiogenesis treatments from the laboratory to clinical practice lies in identifying the role of tissue-specific angiogenic factors. To meet this challenge, there is a great need for innovative experimental methods to investigate the complex mechanisms of tumor angiogenesis. Our research goal is to develop a morphologically and functionally differentiated 3D in vitro tumor-vascular model that will allow investigation of shear stresses-mediated tumor angiogenesis. We hypothesize that hemodynamic stresses of the tumor microenvironment play a regulatory role in expression of angiogenic growth factors, vessel permeability, and tumor vascularization, which may be directly related to endothelial-tumor interactions within the tumor microenvironment. This hypothesis will be investigated through the following specific aims: 1) Develop a novel in vitro tumor vascular model that mimics the structural and hemodynamic tumor environment and enables the measurement and modification of tumor-inherent mechanical stresses. In Specific Aim 1, we will fabricate 3D microfluidic collagen gels for dynamic co-culture of endothelial and cancer cells, characterize the scaffold material properties, and integrate microPIV to quantify wall shear stress within the tumor vascular model. 2) Validate that the in vitro tumor vascular model represents in vivo tumors with physiological fidelity. In Specific Aim 2, we will optimize cell seeding densities, scaffold thickness, and culture conditions to induce important epigenetic characteristics of tumors such as uninhibited 3D proliferation, generation of hypoxic gradients and necrosis, and expression of angiogenic growth factors. 3) Investigate the relationship between shear stress and tumor-endothelial cell cross-talk associated with angiogenesis. In Specific Aim 3, we will determine the effect of varying fluid shear stresses on local cell morphology, proliferation, migration, microvascular permeability, and expression of angiogenic growth factors. Our tumor vascular model will provide the first truly representative in vitro platform for elucidating mechanisms of shear-stress mediated tumor angiogenesis. Our interdisciplinary research team, unique tumor vascular model, and novel hypothesis are the driving innovative components of our strategy.